[unreadable] Circulating tumor cells in blood are detectable in late stage colon cancer patients. However, adequately sensitive and specific methods have not been identified for early diagnosis or detection of micrometastatic cells. Also, current approaches are cumbersome and therefore not suitable for use by clinical diagnostic laboratories. Routine clinical use will require a substantial improvement in rare tumor cell enrichment from blood, identification of an appropriate tumor marker that identifies the majority of early stage patients without false positives or negatives, and an integrated methodology more compatible with clinical laboratory testing. Our ultimate goal is to enable reproducible detection and confirmation of rare colon cancer cells from blood in an economical integrated clinical laboratory test or point-of-care platform. During phase I we will confirm the feasibility of our approach using whole blood spiked with colon cancer cells. We propose a credit-card sized microfluidic cell sorting device for sorting and detecting tumor cells in blood that will be much faster and have high specificity and several orders of magnitude greater sensitivity than current flow cytometry. Individual steps will be performed using on-card fluidic movement and valving logic, with final performance enabled through the design of an integrated microfluidic circuit that automates the process. The completion of our phase I specific aims will result in a bread board platform that will be tested using clinical specimens from colon cancer patients in collaboration with Fred Hutchinson Cancer Research Center. Colorectal cancer affects approximately 147,000 people in the United States each year and is most effectively treated when diagnosed at an early stage. Consequently, colon cancer screening is an effective means for decreasing mortality secondary to colon cancer. Current colon cancer screening methods include either sigmoidoscopy or colonoscopy. However, only 25-35 percent of adults undergo screening because of fear of discomfort from the bowel preparation and, in the case of colonoscopy, the cost of the screening test. The colon cancer screening test we will develop uses a blood specimen for diagnosis to overcome the drawbacks of current screening methods. The approach leverages recent advances in molecular assays together with Micronics' microfluidics and cell sorting technologies to develop an assay that can be utilized in routine clinical or point of care settings. This will result in better screening compliance and save lives through earlier detection. [unreadable] [unreadable]